Electrode



Mar. 13, 1923. 1,448,413

F. J. METZGER ELECTRODE Filed July 29, 1920 .4 ATroRNEYs Patented Mar. 13, 1923.

l PATENT OFFICE.

FLOYD J'. METZGER, OF NEW -YORK, N. Y., ASSIG-N'OR TO .'AIR REDUCTION COMPANY,

` INC., A CORPORATION 0F NEW YORK.

ELECTRODE.

Application filed July 29, 1920. Serial No. 399,882.

To all lwhom it may concern:

` Be it known that I FLOYD J. METZGER, a citizen of the United tates, residing at New York cit in the county of New York, State of New ork, have invented certain new and useful Improvements in Electrodes; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electrodes employed as terminals between which electrical discharges are caused to pass through a gaseous medium or a substantial vacuum and has particular application to the production of luminescent discharges through tubes or lamps which are thereby made to glow. It is to be understood that tubes or lamps are known in which discharges are passed between electrodes through an atmosphere containing gases under various pressures both above and below atmospheric pressure and through a substantial vacuum produced by exhausting the tube or lamp.

In Such tubes or lamps, which may be of lany de'sired shape and which may have the electrodes at opposite ends or in more closely spaced relation, the electrodes have been constructed heretofore of metal, or other conducting material such as copper or carbon for example. These electrodes are connected to lead-in wires which are sealed through the glass of the tube or lamp. If unsupported, the electrodes vibrate more or less, owing to shocks, and are separated from the lead-in wire. It has been suggested to support the electrodes in various ways as by a ring of glass beads disposed between the electrodes and the wall of the tube or lamp, but this introduces additional constructional difficulties, and the arrangement is not wholly satisfactory.

These and other considerations have directed a search for a more satisfactory electrode which may be rigidly supported in the tube or lamp and which will not therefore vibrate and become separated from the leadin wire under repeated shocks. vIt has been discovered as a result of investigations that a very satisfactory electrode may be inexpensively constructed of glass which may be sealed into the glass of the tube or' lamp to form an integral part thereof. To'complete the electrode a sheath of a conducting metal, preferably copper, may be mounted on the glass supportwhich projects into the tube or lamp, the] sheath being connected to a lead-1n wire which is sealed through the glass support. In this manner one or more electrode surfaces may be formed on the glass support for the purposes hereinafter indicated. The copper or other conducting metal is preferably deposited electrolytically on the glass but other methods of applying the metal may be employed. The sheath may be separately formed and spun, or otherwise fastened on the glass support, or the metal may be sprayed onto the glass by means well known to the art.

In. depositing the conducting metal according to the preferred method, the glass support is provided with a conductor sealed therethrough and projecting slightly at the surface to be treated. The glass support is roughened or etched by subjecting 1t to the action of hydrofluoric acid or of a Huoride mixture capable of etching glass in accordance with well understood principles. The etched glass is then dipped in an alcoholic solution of silver nitrate after which the film of silver nitrate adhering to the surface is subjected to the action Ofhydrogen sulphide to produce a conductive coating of silver sulphide. Of course, other means of providing a conductive coating on the glass may be employed. The glass with its conductive coating is arranged as the cathode in an electrolytic bath consisting for example of a copper sulphate solution acidified with nitric acid and a current is passed through the electrolyte to deposit copper on the glass. A closely adherent coating of copper is thus obtained which forms thc permanent conducting surface of the electrode. If metallic coatings other than copper are desired, the electrolyte isv correspondingly modified in accordance with the well known practice of electrolytic deposition of metals. lIf two or more conducting surfaces are desired on the glass support, the surface which it is not desired to plate may be covered. as by a rubber band, or by otherwise insulating a portion of the surface during electrolysis; or the desired portion of the coating may be removed' after deposition of the metal. The projecting conductor sealed through the glass will be in contact with the conductive coating on the surface of the lass. y

An e ectrode produced in the manner'described is ideal for the purposes in view. l It is comparatively light in weight; it may be sealed lnto the glass of the tube or lamp and will not separate therefrom under shocks; the coating may be comparatively thin and will not carry quantities of occluded gases which are detrimental to the objects to be attained and difiicultly removable. The invention facilitates fabrication of the tube or lamp in an inexpensive manner. Electrodes made in accordance with the invention have been employed, particularly in tubes or lamps containing neon, and have proved to be highly satisfactory. The invention, is not however, limited to such use, since it obviously has a broaderapplication.

I t is thel object therefore of the invention to provide a novel, inexpensive and satisfactory electrode adapted for use in tubes and lamps which are illuminated by electrical discharges and for other analogous purposes. Certain applications of the invention are illustrated. by way of example, in the accompanying drawing, in which,

Figure 1 is a view in elevation of a luminescent tube with the improved electrodes embodied therein;

Figure 2 is a view in elevation of an elec` trode;

Figure 3 is a section through anelectrode;

Figure 4 is an elevation of a glow lamp embodying the invention and Figure 5 is a view in elevation of another form of electrode.

Referring to the drawing 5 indicates a tubel which may be under vacuum or filled with a gas at any desired pressure, neon for example. The tube 5 is preferably provided with enlarged ends 6 to receive the electrodes 7 lwhich are made of glass and are sealed into the ends 6 as indicated at 8. The electrodes 7 are provided as hereinbefore described with coatings 9 of conductive metal deposited or otherwise applied to the electrodes, and -with conductors 10 sealed through the wall of the electrode to make contact with theicoating 9. When the two electrodes 9 are connected to a source of current at suitable voltage the tube is caused to glow. As will be readily understood the electrodes form an integral part of the tube and are rigid and not subject therefore to vibration such as ultimately causes breakage of the conductor in tubes rovided with the usual metal electrodes. ccluded gases may be readily driven from the relatively thin coating of conductive metal on the electrode and the preparation of the tube is thus facilitated.

ln Fig. 4 of the drawing a glow lamp is illustrated and consists of a bulb 11 inv which an electrode 12 is supported. The electrode 12 is made of glass and is sealed into the bulb 11 at 13. A shell or coating 14 of conductive metal is provided on the glass electrode 12 and is electrically connected to a conductor 15 which is sealed through the electrode. A' band 16 of conductive metal surrounds the electrode 12 below the coating 14 and is electrically 'connected to a conductor 17 which is sealed through the electrode. The band 16 is spaced from the coating 14 a distance less than the minimum spark gap for the gas in the bulb at the pressure employed and consequently when the conductors are connected to a source of current at suitable volt-age, a glow is set up within the' bulb. The advantages of the glass electrode as hereinbefore described are equally apparent in this form of the invention.

In Fig. 5 another form of electrode is illustrated which may replace the electrode in Fig. 4. 'A spherical or similarly shaped surface 18 of a glass support is divided into two parts and is provided with separate shells or coatings 19 of conductive metal. An extension 2O on one side permits sealing of the electrode in a bulb and provides a conduit for the conductors 21 and 22 which are sealed through the glass andare electrically connected to the-'respective shells or coatings. The space between vthe shells or coatings 19 is less than the minimum spark gap for the gas at the pressure used and consequently when the conductors 21 and 22 100 are connectedto a source of current at suitable voltage the discharge between the elecrodes will produce the desired lighting efect.

The term tube as used in the claims here- 105 with is intended to include tubes, bulbs and receptacles of various shapes in which the electrodes may be supported.

Various changes may be made in the form, arrangement and materials employed with- 11o out departing from the Iinvention which, comprehends a support having a conductive surface and adapted to be sealed by --fusion into a surrounding glass wall to produce a gas tight joint.

ll claim:

1. An improvement in electrodes employed in e'ecting electrical dischar es, which comprises a tube, a support wit in the tube, a sheath of conducting metal on 120 the support, said sheath being relatively thin and therefore comparatively free from occluded gases and a conductor connected to the sheath.

2. An improvement in electrodes em- 125 ployed in effecting electrical discharges, which comprises a tube, a support within the tube, a mating of conducting metal electrolytically deposited on the sup ort, said coating being relatively thin and t ere- 130 the space between said coatingsbeing less than the minimum spark gap for the gas within the tube at the pressure used and conductors connected to the coatings.

4. An. improvement in electrodes employed in eii'ecting electrical discharges,

which comprises a glass support, thin coatings of conducting metal on thesurface of the support, the space between said coatings' being less than -the minimum spark gap -for the gas Within the tube at the pressure used and conductors sealed through the wall of the support and connected to the coatings.

improvement in illuminating devices and the like, depending upon electrica-l discharges. which comprises a chamber, a non-metallic support fused int the wall of said chamber, a coating oi conducting metal on the support, said coating being divided to provide two conducting surfaces, the space between -said surfaces being less than the minimum spark gap for the gas within the tube at the pressure used and conductors connected to the respective conducting surfaces.

6. An improvement in illuminating devices and the like, depending upon electrical discharges', which comprises a chamber, a non-metallic support fused int`0 the wall of said chamber, a coating of conducting metal on the support, said coatingbeing divided to provide two conducting surfaces, the space between said surfaces being less than the minimum spark gap for the gas within the tube at the pressure used and conductors connected to the respective conducting surfaces, said conductors being sealed through the wall of the support. Y

In testimony whereof I aiix my signature.

FLOYD J. METzGER 

